I am facing this issue where the thumbnail view does not refresh when changing the thumbnail scale.
-First open a multiple page TIFF
-Size the window so that scroll bars appear in the thumbnail view
-Change thumbnail size to large (or if large then change to small)
-You will notice that scroll bar does not change, so you cannot scroll to view all of the thumbnails until the window size or splitter size is changed.
Work around to this is to increase width of thumbnail viewer by 1 pixel and then reduce it by 1, but this doesn't happen to be a descent solution.
1. Open ImagingDemo.exe
2. Once window opens decrease its size to smaller
3. Now open 10 or more page tiff
4. Open menu View > Thumbnail Viewer Settings
5. Change scale to large > ok
6. You will notice there is no scrollbar in the thumbnail area of left
To fix this, just resize the thumbnail area a bit and it will now show a scroll bar.